Method of fabricating a flow control device

ABSTRACT

Semi-spherical supports are used in the piercing of small, consistently sized holes in a soft metal. In particular, a flow control device, such as an orifice plate, can be fabricated with small, consistently sized flow apertures to regulate flow in a gas flow regulating device. By using semi-spherical supports, the need for hand-punching and real-time flow calibration can be avoided and automated machinery with a tapered piercing tool can be used to fabricate the flow control device.

RELATED APPLICATIONS

This application is a Continuation-In-Part of U.S. application Ser. No.08/941,356 filed Sep. 30, 1997 (now U.S. Pat. No. 6,053,056), whichclaims priority to U.S. Provisional Application No. 60/029,624 filed onOct. 25, 1996, the teachings of which are incorporated herein byreference in their entirety.

BACKGROUND

In a medical setting, oxygen can be delivered to a patient from acryogenic vessel, high pressure gas storage vessel or other controlledpressure delivery sources, such as a hospital delivery system. Such anoxygen delivery system includes an adjustable flow regulator to select aflow rate of oxygen to the patient. Adjustable flow regulators typicallyinclude a circular orifice plate having a plurality of apertures ofvarying sizes through which the oxygen can flow.

In order to create an aperture that allows a certain flow rate, users ofprior art techniques typically create an undersized aperture using ahand tool, measure the flow rate, and subsequently increase the aperturesize and measure the flow rate until gas flows at the desired rate.Other prior art methods utilize needle valves, stamping or compressionof a large aperture, fabrication and assembly of discrete components,blockage of a flow conduit by a ball or tapered pin, photoetching of athin metal disk that is subsequently attached to a thicker plate, orother largely manual methods.

To obtain an accurate flow rate, a real-time flow measurement istherefore made of each aperture during fabrication. Because this islargely a manual process, accurate registration is difficult to achieve,sometimes yielding a secondary aperture proximate to the main apertureto produce the proper flow rate. If the flow rate of a particularaperture is greater than a desired flow rate, then the entire part isrejected.

SUMMARY

Prior art techniques suffer from at least two disadvantages. First, theyare time-consuming and labor intensive processes. Second, they do nottake full advantage of the fact that flow rates are proportionallyrelated to hole sizes.

Orifice plates can be manufactured having flow apertures that are formedto have accurate dimensions. As such, real-time measurement and repairis unnecessary. Consequently, every orifice plate can be identicallyfabricated, within allowed tolerances, using automated machinery. Inaddition, a complete flow control device can be manufactured from asingle piece of material—the orifice plate.

An orifice plate can include a rigid circular plate of material, such asbrass or other soft metal, having a first (bottom) surface and a second(top) surface. A counter bore can yield a domed support structure in thematerial at each flow aperture location. Specifically, the domed supportstructure can have a partial ellipsoidal, or conical shape. Inaccordance with one aspect, the domed support structure has asemi-spherical shape. The counter bore thus defines a support structurehaving an open base at the first (bottom) surface and an apex proximateto the second (top) surface. Prior art attempts at piercing thin-walledorifice plates have failed due to the lack of such a support.

A flow aperture can then be formed through the material from the second(top) surface and registered to the apex of the support structure. Inparticular, there may be a plurality of apertures, each aperture havinga respective size and registered to an apex of a respective supportstructure.

The support structures and the apertures can be created by acomputer-controlled machine. In particular, the computer can control apiercing tool which is automatically registered to the apex of thesupport structure and inserted through the thinned material to form theflow aperture. By using a computer-controlled process, orifice platescan be repeatedly reproduced to be substantially identical, withinpermitted tolerance.

In accordance with a particular embodiment of the invention, the orificeplate can be used in a flow regulator. In a flow regulator, an inflowconduit provides oxygen or another gas at a substantially constantpressure and an outflow conduit provides the gas at a specific flowrate. The orifice plate is coupled between the inflow conduit and theoutflow. In particular, the flow regulator can adjustably control theflow of medical oxygen from a supply vessel to a patient. In such anapplication, the flow apertures vary in size from about 0.0007 squaremillimeters or less to about 0.8 square millimeters and the thickness ofplate material at the apex of the dome structure is about 0. 1millimeter. Flow rates of {fraction (1/32)} liters per minute (lpm) canbe reliably achieved from a 50 pounds per square inch (psi) oxygensupply. Other dimensions can be used for other applications.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the method of fabricating a flow controldevice, including various novel details of construction and combinationof parts, will now be more particularly described with reference to theaccompanying drawings and pointed out in the claims. It will beunderstood that the particular methods of fabricating a flow controldevice embodying the invention are shown by illustration only and not asa limitation of the invention. In the accompanying drawings, likereference characters refer to the same parts throughout the differentviews. The drawings are not necessarily to scale, emphasis instead beingplaced upon illustrating the principles of the invention. The principlesand features of the invention may be embodied in varied and numerousembodiments without departing from the scope of the invention.

FIGS. 1A-1B are a simplified perspective view of a typical cryogenic andhigh pressure supply vessel, respectively.

FIG. 2 is a bottom-side perspective view of a particular orifice plate.

FIG. 3 is a schematic diagram of a particular orifice plate embodied inan illustrative flow regulator.

FIGS. 4A-4B are cross-sectional diagrams of a support structure having afirst and second flow aperture of FIG. 2, respectively.

FIGS. 5A-5D are process flow diagrams of a particular method of formingthe flow apertures of FIG. 2.

FIG. 6 is a cross-sectional diagram of another embodiment of a supportstructure.

FIG. 7 is a cross-sectional diagram of yet another embodiment of asupport structure.

FIG. 8 is a cross-sectional diagram of still another embodiment of asupport structure.

FIG. 9 is a perspective view of a particular embodiment of the inventionemploying a pyramidal piercing tool.

FIG. 10 is a cross-sectional diagram of a formed flow aperture showing aparticulate matter trap.

DETAILED DESCRIPTION

FIGS. 1A-1B are a perspective view of a typical cryogenic and highpressure supply vessel, respectively. The vessel 2, 2′ can be an oxygensupply vessel. An adjustable flow regulator 6, 6′ is coupled to a supplyconduit 4 from the vessel 2, 2′. Within the flow regulator 6, 6′ is acircular orifice plate (described below), which can have a plurality ofdiscrete flow settings. Each flow setting is registered to a respectiveflow aperture. Each aperture supports a specific flow rate through anoutflow conduit 8, 8′, as indicated by the setting of an adjusting dial5.

FIG. 2 is a bottom-side perspective view of a particular orifice plate10. As illustrated, the orifice plate includes eleven flow apertures 12a-12 k corresponding to eleven discrete flow settings. Each flowaperture 12 a-12 k has a respective flow area corresponding to apreselected flow rate. An optional mounting hub 18 can be utilized toregister the orifice plate 10 to the adjusting dial 5 (FIG. 1). Althougheleven flow apertures are illustrated, corresponding to elevenselectable flow rates, a greater number or a smaller number of flowapertures 12 can be provided, depending on the intended application.

In some applications, only one flow aperture 12 may be required. In suchapplications either a fixed flow rate is specified or the flow rate maybe adjusted by varying the supply pressure of the gas. In any event, theflow control device may be fabricated integrally with the regulatorbody—without a separate, rotatable orifice plate.

FIG. 3 is a schematic diagram of a particular orifice plate 10 embodiedin an illustrative flow regulator 6. The orifice plate 10 separates asupply conduit 4 supplying gas at an essentially constant operatingpressure from an outflow conduit 8. It will be understood that theorientation of the orifice plate can be reversed from that shown. Theillustrated orientation, however, offers particular advantages. First,the piercing tool deflects the orifice plate material into the counterbore 14. That deflected material tends to create a particular mattertrap, as will be discussed below.

It will also be understood that the orifice plate 10 can be adapted foruse in any flow regulator which uses a prior art orifice plate.Particular embodiment of flow regulators having an orifice plate asdescribed herein are commercially available from Inovo, Inc. of Naples,Fla. Specific examples of Inovo regulators are described in U.S.application Ser. No. 09/342,953 (filed Jun. 29, 1999), U.S. ProvisionalApplication No. 60/091,127 (filed Jun. 29, 1998), U.S. ProvisionalApplication No. 60/119,745 (filed Feb. 9, 1999), U.S. ProvisionalApplication No. 60/124,704 (filed Mar. 15, 1999), and U.S. ProvisionalApplication No. 60/127,961 (filed Apr. 6, 1999), the teachings of whichare all incorporated herein by reference in their entirety.

Returning to FIG. 2, each flow apertures 12 a-12 k is centered relativeto a respective counter bore 14 a-14 k. As viewed from the bottom side,the counter bores 14 a-14 k create a domed support structure from theplate material. As the term is used herein, a domed structure is athree-dimensional structure having an open base and a wall tapering toan apex. Examples of dome wall shapes include partial ellipsoidalshapes, such as semi-spheres and elliptic paraboloids, and conicalshapes. A cross-section taken through the apex reveals an arched-shapesupport wall, which can include semicircular, semi-oval, or triangularshapes. Other suitable shapes may be found by routine experimentation.

FIGS. 4A-4B are cross-sectional diagrams of a first and a second flowaperture 12 a, 12 b of FIG. 2, respectively. As illustrated, both flowapertures 12 a, 12 b have a circular flow area and the first flowaperture 12 a has a smaller diameter than the second flow aperture 12 b.As illustrated, the principle axis of each flow aperture 12 a, 12 b isregistered to a respective apex of a domed structure 14 a, 14 b having asemi-spherical wall 15 a, 15 b. Precise registration between the flowapertures 12 a, 12 b and the apex of the domed structures 14 a, 14 b,however, is not critical.

A primary purpose of the domed support is to allow rapid, automaticpiercing of apertures to provide a specified flow rate, such between atleast about 0.03 millimeter (0.001 inch) and 1 millimeter (0.039 inch)in diameter. The predictability of the disclosed method is particularlyimportant for forming the smaller apertures for the lowest flow rates.The smaller diameter apertures are especially useful in pediatricmedical oxygen regulators, where low flow rates may be desired. Usingthe disclosed fabrication method, small aperture sizes, and thus lowflow rates, can be obtained that cannot be realized using other knownmethods. For example, oxygen flow rates of less than ¼ lpm, at leastdown to {fraction (1/32)} lpm, can be reliably obtained from anoperating pressure of 50 psi, using the disclosed method. Precision flowapertures with tight tolerances ensures that the most vulnerablepatients, including premature infants, can receive an appropriate andaccurate dosage of oxygen.

When a tapered tool is employed, the computer controls the size of theaperture by controlling the depth of the pierce. This eliminates theneed for hand-piercing and real-time flow calibration, which arenecessary without the use of domed supports. Instead, the flow apertures12 can be fabricated using automated piercing machinery.

Although prior art techniques have included counter bores, they usedrelatively large cylindrical-shaped counter bores. Those counter boreswere used to thin a region of the plate material and a flow aperture wasthen formed through this thinned material. Because of the relativelylarge target area of the thinned material (i.e., an area of asubstantially constant thickness), precise alignment between a piercingtool and the bore was not required. Due to flex and rebound of therelatively thin material being pierced, however, the size of eachaperture, and therefore its flow rate, could not be accurately achieved.The machining of the relatively large cylindrical-shaped counter boresalso tends to warp and weaken the extended thinned area of material,which also affects the size of the flow apertures.

It should be noted that the domed support structure 14, however, canhave a flat ceiling. That is, there can be a thinned region ofrelatively constant thickness between the top of the counter bore andthe top surface of the plate. That flat ceiling, however, is limited insize so as to inhibit warping during machining and significant flexingand redounding during the piercing operation. In fact, as the area ofthe flat ceiling approaches the area of the flow aperture, tapering ofthe walls may be unnecessary. Those dimensions can vary depending on thethickness of the thinned material and the size of the desired flowaperture. This implies that the counter bores may not be identical. Eachcounter bore dimension would ideally accommodate one (or a few) flowaperture dimension.

FIGS. 5A-5D are process flow diagrams for creating a particular flowaperture in accordance with the invention. The area of material 16 beingpierced should be sufficiently thin to allow a tool to make a holewithout breaking the material or a piercing tool 20. To facilitate thattask, the orifice plate is made of brass or another soft metal. Thethinned material may be less than about 0.3 millimeter (0.01 inch)thick. To achieve this thickness, as illustrated in FIG. 5A, a counterbore 14 having a diameter D of about 3.2 millimeters (0.125 inch) isapplied to the orifice plate 10 of greater thickness. The distance zbetween the apex of the wall 15 and the opposite surface 16 of theorifice plate 10 is then thinned to about 0.1 millimeter (e.g., 0.0035inch). It will be understood that the exact dimensions are a designchoice of the user and can depend on the materials used for the orificeplate 10 and the piercing tool 20.

Referring to FIG. 5B, the piercing tool 20 is placed in position underthe control of an automated machine 30. Specifically, the central axisof the piercing tool 20 is registered with the apex of thesemi-spherical void 14. The piercing tool 20 can have a conical,pyramidal or other shape suitable for piercing the orifice plate 10. Asillustrated, the piercing tool 20 is tapered at an angle, which can bechosen by the user. For example, the angle can be suitably chosen to beabout 7-10 degrees.

Referring to FIG. 5C, the piercing tool 20 is forced into the orificeplate 10. As the piercing tool 20 goes deeper, a larger hole is created.By using a semi-spherical support, there is little or no flex orresulting rebound from applying the piercing tool 20 to the structure.Downward forces are dispersed down the wall into progressively thickermaterial.

Referring to FIG. 5D, a circular flow aperture 12 having a diameter dhas been created using a conical piercing tool 20. For example, the flowaperture 12 can have a diameter d of 1 millimeter±0.006 millimeter(e.g., 0.003 inch±0.0002 inch). By using a semi-spherical support, therequired tool depth to achieve a given aperture diameter is predictable,which permits the automated fabrication of flow apertures. Although theaperture 12 is illustrated as having a circular flow area, the actualshape of the aperture 12 depends on the shape of the piercing tool 20.Accordingly, the flow aperture 12 can have a circular, oval, polygonalor any other suitable shape.

In accordance with a particular embodiment, both the counter bores 14and the flow apertures 12 are formed using a single Computer NumericalControl (CNC) machine. Sample orifice plates are selected for qualitycontrol inspection, which includes off-line flow rate measurements.

FIG. 6 is a cross-sectional diagram of another embodiment of a supportstructure. As illustrated, a counter bore 14′ yields anellipsoidal-walled support structure 15′ in the plate material 10. Notethat as the diameter of the counter bore 14′ approaches the diameter ofthe flow aperture 12, the tapered section of the wall will be destroyedby the piercing tool.

FIG. 7 is a cross-sectional diagram of yet another embodiment of asupport structure. As illustrated, a counter bore 14″ yields aconical-walled support structure 15″ in the plate material 10. Such anembodiment may be particularly useful for supporting extremely smallflow apertures.

FIG. 8 is a cross-sectional diagram of yet another embodiment of asupport structure. As illustrated, two opposing counter bores 141, 142are formed in the plate material 10. The flow aperture 12 is formed bypiercing the thinned plate material between the apexes of the counterbores 141, 142. Although the counter bores 141, 142 are illustrated ashaving semi-circular walls 151, 152, any of the aforementioned shapes orcombinations can be substituted.

FIG. 9 is a perspective view of a particular embodiment employing apyramidal piercing tool 20′. As illustrated, the piercing tool 20′yields a triangular aperture 12′ in the plate material 10. The aperture12′ is centered on the apex of a respective counter bore 14 (shown inphantom). Although the pyramidal piercing tool 20′ is shown as havingthree sides, it will be understood that the piercing tool 20′ can have agreater number of sides.

FIG. 10 is a cross-sectional diagram of a formed flow aperture showing aparticulate matter trap. The piercing operation does not necessarilyremove material. Instead, the piercing tool 20 ruptures the thinnedmaterial 10 to form the flow aperture 12. This operation forces shardsof material 40 downward into the void 14. Those shards of material 40project outward from the wall 15 to create pockets 45. When the gas flowis from the bottom to the top, as shown, the pockets 45 operate to trapparticulate matter that may be in the gas flow, thereby inhibiting thetransfer of such particulate matter through the flow aperture 12.

An added advantage of forming the flow aperture 12—instead of machiningit—is that the top surface 16 of the orifice plate is smooth. A machined(e.g. drilled) aperture would have burrs. Without such a sharp boundary,the orifice plate described herein does not require additional finishingand can directly interface with o-rings in an assembledregulator—without damaging the o-ring. That advantage further reducespart counts and manufacturing steps.

EQUIVALENTS

While the method of fabricating a flow control device has beenparticularly shown and described with reference to particularembodiments, it will be understood that those skilled in the art thatvarious changes in form and detail can be made without departing fromthe spirit and scope of the invention as defined by the appended claims.For example, the method of fabricating a flow control device made inaccordance with the invention can be used in other gas or liquid flowdevices.

These and all other equivalents are intended to be encompassed by thefollowing claims.

What is claimed is:
 1. A method of fabricating a gas flow controldevice, comprising: in a rigid plate of material having a top surfaceand a bottom surface, creating a domed support structure in the platefrom the bottom surface; registering a tool to the support structure atthe top surface; and forming an aperture by piercing the tool throughthe material from the top surface to the support structure, the aperturedimensioned to yield a selected flow rate of a gas through the aperturefor a given input pressure of the gas.
 2. The method of claim 1 furthercomprising determining the aperture dimension without real timemeasurement of the flow rate of the gas through the aperture.
 3. Themethod of claim 1 wherein creating a support structure, registering atool and forming an aperture are repeated to form a plurality ofannularly-spaced apertures, each aperture registered to a respectivesupport structure.
 4. The method of claim 3 wherein the supportstructures are substantially identical.
 5. The method of claim 3 whereineach aperture has a respective area at the top surface.
 6. The method ofclaim 1 wherein the aperture has a polygonal shape.
 7. The method ofclaim 1 wherein creating a support structure comprises forming a partialellipsoidal shape in the plate.
 8. The method of claim 1 wherein thematerial is a soft metal.
 9. The method of claim 1 wherein the piercedmaterial is about 0.3 millimeter or less in thickness.
 10. The method ofclaim 1 wherein registering a tool comprises positioning the tool inresponse to computer commands.
 11. The method of claim 1 whereinregistering a tool comprises registering the tool to an apex of thesupport structure.
 12. The method of claim 1 wherein creating a supportstructure comprises machining opposing counter bores in the plate andforming the aperture comprises forming an aperture through the platebetween the opposing counter bores.
 13. The method of claim 1 whereinforming the aperture comprising controlling the tool by a computer toform an aperture to yield the selected flow rate.
 14. A method offabricating a flow control device for metering the flow of a gas,comprising: providing a rigid plate of material having a nominalthickness bounded by a top surface and a bottom surface; creating adomed support structure in the plate from the bottom surface;registering a tool with the support structure; selecting a flow rate ofa gas from a given input pressure of the gas; and forming a flowaperture by piercing the tool through the material from the top surfaceto the support structure so as to yield the selected flow rate throughthe flow aperture.
 15. The method of claim 14 further comprisingcompleting the orifice plate without real time measurement of the flowrate of the gas through the flow aperture.
 16. The method of claim 14wherein creating a support structure, registering a tool, selecting aflow rate and forming the flow aperture are repeated to form a pluralityof flow apertures annularly spaced about the plate, each flow aperturecoaxially registered with a respective support structure.
 17. The methodof claim 16 wherein the support structures are substantially identical.18. The method of claim 16 wherein each flow aperture has a respectivedimension.
 19. The method of claim 18 wherein the flow aperture has apolygonal shape.
 20. The method of claim 14 wherein forming a supportstructure comprises forming a partial ellipsoidal shape in the plate.21. The method of claim 14 wherein the material is a soft metal.
 22. Themethod of claim 14 wherein the pierced material is about 0.3 millimeteror less in thickness.
 23. The method of claim 14 wherein registering atool comprises positioning the tool in response to a computer commands.24. The method of claim 14 wherein registering a tool comprisesregistering the tool to an apex of the support structure.
 25. The methodof claim 14 wherein creating a support structure comprises machiningopposing counter bores in the plate, and forming the flow aperturecomprises forming a flow aperture through the plate between the opposingcounter bores.
 26. The method of claim 14 wherein the domed supportstructure is machined to have an apex, wherein the thickness of materialbetween the support structure and the top surface is variable andwherein the material is at a minimum thickness between the top surfaceand the apex.
 27. The method of claim 26 wherein the tool is taperedsuch that a thicker portion of the tool is registered with a thickerportion of the material.
 28. The method of claim 14 wherein forming aflow aperture further yields a particulate matter trap proximate to theflow aperture.
 29. A method of fabricating a gas flow control device,comprising: in a rigid plate of material having a top surface and abottom surface, machining opposing counter bores in the plate to thinthe material to about 0.3 millimeter or less; registering a taperedpiercing tool to the counter bores from the top surface; and forming anaperture by piercing the tool through the material between the opposingcounter bores.
 30. The method of claim 29 wherein forming the aperturefurther comprises dimensioning the aperture without real timemeasurement of a flow rate of a gas through the aperture.
 31. The methodof claim 29 wherein machining opposing counter bores, registering atool, and forming an aperture are repeated to form a plurality ofannularly-spaced apertures, each aperture registered to respectivecounter bores.
 32. The method of claim 31 wherein the counter bores aresubstantially identical.
 33. The method of claim 31 wherein eachaperture has a respective area at the top surface.
 34. The method ofclaim 29 wherein the aperture has a polygonal shape.
 35. The method ofclaim 29 wherein creating a counter bore comprises forming a partialellipsoidal shape in the plate.
 36. The method of claim 29 wherein thematerial is a soft metal.
 37. The method of claim 29 wherein the tool isa piercing tool and the step of forming an aperture comprises piercingthe material.
 38. The method of claim 29 wherein registering a toolcomprises positioning the tool in response to computer commands.
 39. Themethod of claim 29 wherein registering a tool comprises registering thetool to an apex of the counter bore.
 40. The method of claim 29 whereinforming the aperture comprising controlling the tool by a computer toform an aperture to yield a selected flow of a medium introduced at agiven input pressure.
 41. A method of fabricating a gas flow controldevice, comprising: in a rigid plate of material having a top surfaceand a bottom surface forming a plurality of annularly-spaced apertures,each aperture registered to a respective support structure, byrepeatedly: creating a domed support structure in the plate from thebottom surface; registering a tool to the support structure at the topsurface; and with the tool, forming an aperture through the materialfrom the top surface to the support structure, the aperture dimensionedto yield a selected flow rate of a medium through the aperture for agiven input pressure of the medium.
 42. The method of claim 41 furthercomprising completing determining each aperture dimension without realtime measurement of the flow rate of the medium through the aperture.43. The method of claim 41 wherein the support structures aresubstantially identical.
 44. The method of claim 41 wherein eachaperture has a respective area at the top surface.
 45. The method ofclaim 41 wherein the aperture has a polygonal shape.
 46. The method ofclaim 41 wherein creating a support structure comprises forming apartial ellipsoidal shape in the plate.
 47. The method of claim 41wherein the material is a soft metal.
 48. The method of claim 41 whereinthe tool is a tapered piercing tool and the step of forming an aperturecomprises piercing the material.
 49. The method of claim 41 whereinregistering a tool comprises positioning the tool in response tocomputer commands.
 50. The method of claim 41 wherein registering a toolcomprises registering the tool to an apex of the support structure. 51.The method of claim 41 wherein creating a support structure comprisesmachining opposing counter bores in the plate and forming the aperturecomprises forming an aperture through the plate between the opposingcounter bores.
 52. The method of claim 41 wherein forming the aperturecomprising controlling the tool by a computer to form an aperture toyield the selected flow rate.
 53. The method of claim 41 wherein formingthe domed support structure comprises thinning the plate material to athickness of about 0.3 mm or less.
 54. A method of fabricating a flowcontrol device for metering the flow of a gas, comprising: providing arigid plate of material having a nominal thickness bounded by a topsurface and a bottom surface; forming a plurality of flow aperturesannularly spaced about the plate, each flow aperture coaxiallyregistered with a respective support structure, by repeatedly: creatinga domed support structure in the plate from the bottom surface;registering a tool with the support structure; selecting a flow rate ofa gas from a given input pressure of the gas; and with the tool, forminga flow aperture through the material from the top surface to the supportstructure so as to yield the selected flow rate through the flowaperture.
 55. The method of claim 54 further comprising completing theorifice plate without real time measurement of the flow rate of the gasthrough the flow aperture.
 56. The method of claim 54 wherein thesupport structures are substantially identical.
 57. The method of claim54 wherein each flow aperture has a respective dimension.
 58. The methodof claim 57 wherein the flow aperture has a polygonal shape.
 59. Themethod of claim 54 wherein forming a support structure comprises forminga partial ellipsoidal shape in the plate.
 60. The method of claim 54wherein the material is a soft metal.
 61. The method of claim 54 whereinthe tool is a piercing tool and forming a flow aperture comprisespiercing the material.
 62. The method of claim 54 wherein registering atool comprises positioning the tool in response to a computer commands.63. The method of claim 54 wherein registering a tool comprisesregistering the tool to an apex of the support structure.
 64. The methodof claim 54 wherein creating a support structure comprises machiningopposing counter bores in the plate, and forming the flow aperturecomprises forming a flow aperture through the plate between the opposingcounter bores.
 65. The method of claim 54 wherein the domed supportstructure is machined to have an apex, wherein the thickness of materialbetween the support structure and the top surface is variable andwherein the material is at a minimum thickness between the top surfaceand the apex.
 66. The method of claim 65 wherein the tool is taperedsuch that a thicker portion of the tool is registered with a thickerportion of the material.
 67. The method of claim 54 wherein forming aflow aperture further yields a particulate matter trap proximate to theflow aperture.
 68. The method of claim 54 wherein forming the domedsupport structure comprises thinning the plate material to a thicknessof about 0.3 mm or less.